So two or so month ago my ex handed me a pickle jar with cloudy water and 2 fantail goldfish in it. In his mind all I had to do was to put them to my other fish ....! Yeah right, 2 giant goldfish with a bunch of tropical fish! In a 10 gal tank!!!!He had kept them in a 26 gal tank but... no regular water changes, full I mean really full of algae and a water level less than half the tank... I do not know how those fish were able to stay alive.

Long story short I took them home, what else could I do they have been in that jar for over an hour already.So I emptied a 20gal storage tote as temporary holding tank and filled it with treated tap water. I only had my tiny old 10 gal filter at that time, better than nothing I thought. With an air pump I built an additional DIY sponge filter (*proud*) to create more surface for the beneficial bacteria. I guess thanks to the filter material I took from my 10g tank I was able to cycle the "tote-tank" in record time.

A month ago my Ex finally brought me the 26 gal tank. What a mess, the glass was covered in dried algae. The little bit gravel and water in the bottom had a really unpleasant odor to it, so I just dumped it all. I didn't think I would be able to remove those algea and safe that tank but.... soaking in strong vinegar solution and a lot of scrubbing actually did it! Having now a nice tank I went and got some gravel and an additional 20/30 Gallon filter, set it all up and moved Red and Yellow into their nice and clean new home.

Then, about 3 weeks ago I discovered one problem : The nitrate level was quiet high! I have zero in my 10 gal tank, but this 26 gal tank had 80ppm. I managed to calm myself, no need to panic girl, just do a nice big water change. Now this 26g is in my basement and I have no water access down there, which means I have to carry the all water in buckets downstairs and the waste water back upstairs. It is quiet a workout, I tell ya!When I checked again after a 60ish % water change, the test still showed about 40ppm nitrate. Bummer I thought, gotta do another tomorrow. Now after another about close to 90% wc the next day, the nitrate went down to 20ppm. Bleh, I expected a result more closer to zero. Now I know goldfish are messy (*whine* and I never wanted one) and recommended is a 30g tank but the filter are working, I have 0 ammonia and 0 nitrite why on earth does the nitrate not go down after several big water changes? It pops right back up to 40ppm a day after the wc. For 3 weeks now every 3 days I keep hauling bucket after bucket downstairs but I just cant get the problem solved! Everything is clean, no mess in the filter, just a thin layer of gravel which I vacuum every week, only feed once a day what they can eat and I tested the tap water too, zero!

As my last attempt, I read that some plants are good nitrate eater, I went out and collected some duckweed a few days ago. The java moss I have in the tank obviously doesn't do it and I wasn't able to get my hands on a philodendron plant. Unfortunately no change so far, maybe I need more duckweed? Or more patience? The thought of getting a hose down the basement crossed my mind, at least then I don't have to carry water buckets downstairs anymore.

Last edited by Tashina on Sat Sep 17, 2016 1:25 am; edited 2 times in total (Reason for editing : a few words added, picture added)

I am not sure if it would work, seeing the tap faucet would be one level up from where the tank is located, but there are water change hoses called "Pythons". Did you ever hear of these? You hook it up to the faucet and it will drain water from the tank into the sink, and with a turn of a lever on the hose you can fill the tank right up again.

As for plants, as far as I know goldfish can eat the roots of plants, they might unearth plants from their location in the substrate, or maybe I got the species wrong. However you can pop the roots of a nice big established plant into the filter compartment (some people use spider plants!). The only problem I can see if you use any potted plants from your house or garden center is that they may have fertilizer on/in them that may be harmful to your tank. But if you get plants from an online aquatic plant seller, or your local fish store, you should be OK.

The tank is kind of small for two goldfish, especially if the fish are large. Maybe you can pick up a 40 or 55 gallon, second hand perhaps? This would help keep the nitrate levels more manageable. In the meantime I would reduce the amount you feed, you can also incorporate a day of fasting.

Another thought, how long do you keep the lights on? Plants will need light to be able to function/eat up the nitrates! Light is somewhat a double-sided sword, first you need to have the right light, and then you need to find a balance between how long to leave the lights on so the plants are thriving but where algae does not get out of hand. I've added a plant light in my Betta tank, but I have tons of plants in there. Sometimes I get a bit of algae on the side of the tank that faces the window around the corner. The tank gets between 6-8 hours of artificial light every day. A nerite snail helps control the algae build up in there as well.

Goldfish a large flush feeders. I consider them the "cows" of the aquarium fish world. By that I mean that they require a lot of bulk food and they excrete a lot of bulk waste.

My first inclination is to increase the amount of biofiltration. I am not clear on what type of filter you have, but you will need high capacity on the heavy duty side. If you read some of @SBenson11 posting you will see that he ultrafilters his koi aquariums. In fact, if there was a fish the ever needed heavy bio-filtration, these are the ones.

Ok. Plants are good. Live plants even better. You can search posting here on some of the best nitrate converters. You may have some already. Java moss, duckweed, floating plants are a great start.

Water changes at this stage will cause fluctuations since I do not think your tank has been through enough cycles to really be stable. So patient will be required, in that over the next few months you will eventually get a stable cycle. I have posted on the nitrogen cycle in many previous posts so I will not cite the references.

Water. I am not sure what type of municipal water you have. If you have a chloramine system, you will of course have high nitrates. If you have an infused chlorine system, then you have less load from the outside water supply.

My thoughts. Looking forward to other nitrogen and koi experts on this.

I have been successful keeping goldfish in a planted tank and with a canister filter. Goldfish eat plants so you cannot put anything in there. The plants that work well are: java ferns, anubias, cryptocorynes and amazon swords. These do not require a lot of light; actually I am not using the aquarium light as the tank gets enough natural light.

To facilitate the growth of cryptocorynes and the amazon swords, make a dirt tank and add some laterite. The laterite will absorb the fish waste and release the nutrients to your plants.

Thank you all for your input Right now the level seems to stay between 20 and 40ppm with a water change every 4-5 days which is an improvement. The duckweed I put in there seems to do well (I put it in a breeding box so the goldfish buggers cant eat it) Im hoping it will grow and use up more nitrates. I read that floating plants can take CO2 out of the air so I dont have to add any to the water.I would love to get a bigger tank for them, because then ...*drool* .... I could use this 26g for my community tank

What are you using to test water parameters? From your original post the nitrate only going in half after a 90% water change isnt right. Have you tested your source(tap) water? You will have substantial nitrate creep, but no chance of 40 in a day, not even two. Tank is small, fish do have fair sized bioload, but the numbers dont add up properly. Ideally, you need a bigger tank and better filtration. You should strive for a maximum nitrate level of 20ppm. When there, a 50% change will bring you to 10.... IF your test kit is reading properly(dont use test strips) and your tap water is nitrate free, or very close to.

However yes he is right Goldfish are notoriously poor processors of the food they eat. They don't have a stomach like we do to hold the food as it digested and absorbed into our bodies. For gold fish the digestion takes place in their intestine as it's flies out the back door pretty much as it came in. Which is why they are best feed in small doses several times a day.

My first though was that the Nitrates is coming from your tap water, but if your other tank is low than that's not it. Your ammonia is 0 and nitrite 0, so your tank is cycled and operating fine. So I am comfortable with the amount of filtration you have, but you can never have to much with goldfish.

What it all boils down to is the Nitrates is just the end result of the nitrogen cycle in your tank. So there are two ways to get rid of it, water changes and plants to use it up. When I say plants I mean floating plants or plants outside the tank with their roots in the water.

As one of my instructors once said "The solution to pollution is dilution". I am a big believer in the benefits of regular water changes.

Also have a look at how much you are feeding them, just because they eat what your giving them doesn't mean they need it.

Rofl @ Fores, thanks for the idea Thanks again for the info and suggestions. So far the nitrate now stays under 40ppm with weekly waterchanges of around 50%. I did test my tab water, zero nitrate and my 10g has no nitrate either so the tests must be working somewhat. But I will go and pick up some liquid tests next time in town and see what level they will show.about the Chinese Buffet (lol): I only fed them once a day (with a day off every few days) around 10 of those little goldfish pellets for both of them, could that be really to much? There is nothing else in this tank they could eat, no algae, no plants except javamoss and the duckweed is in a breeding box out of their reach. Which brings up another question: how do you determine how much is to much and how much is the minimum a fish should eat? They wont have rips sticking out when they don't get enough or do they kinda?

Tashina wrote:Rofl @ Fores, thanks for the idea Thanks again for the info and suggestions. So far the nitrate now stays under 40ppm with weekly waterchanges of around 50%. I did test my tab water, zero nitrate and my 10g has no nitrate either so the tests must be working somewhat. But I will go and pick up some liquid tests next time in town and see what level they will show.about the Chinese Buffet (lol): I only fed them once a day (with a day off every few days) around 10 of those little goldfish pellets for both of them, could that be really to much? There is nothing else in this tank they could eat, no algae, no plants except javamoss and the duckweed is in a breeding box out of their reach. Which brings up another question: how do you determine how much is to much and how much is the minimum a fish should eat? They wont have rips sticking out when they don't get enough or do they kinda?

I'd suggest that it's a function of the waste they produce. It's not a huge tank, and even two goldfish can produce huge waste.

Many fish can go up to two weeks without food and not result in any major negative effects. I used to feed everyday and then cut out one day a week. I regularly skip every other day now. Everything seems to go smoothly like this. Just keep up the big water changes. Steve really hit the nail right on the head.

You probably do this already, but thought I just mention it anyhow. When you do the water changes make sure to get the gravel substrate vacuumed up well, any waste left behind will contribute raising the nitrate levels as well.

Poppy wrote:You probably do this already, but thought I just mention it anyhow. When you do the water changes make sure to get the gravel substrate vacuumed up well, any waste left behind will contribute raising the nitrate levels as well.

Interesting point,

I don't have any kind of substrate in my Goldfish/Koi tanks. However when I did I would use a Python and plunge into the gravel all over the tank while removing the water. This would suck up all the "STUFF" left behind that only fouls the water.

Steve that is exactly what I do with every water change. I dont have Python hooked to a faucet but I use a syphon and gravity to get the water out while vacuuming the gravel. I only have a thin layer of gravel in there, just enough to cover the glass which makes it easy to get all the waste out.I got a liquid test today and I believe (I have a hard time matching the color) it shows around 10ppm after a 60% water change yesterday. So I either got it fixed or my old tester showed higher levels than there actually were. Time will tell now how high the level goes till the next scheduled water change and hopefully I can put the nitrate issue in this tank to rest! Thanks again everyone for your informative and always friendly support, so good to have you all